GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 237-20
Presentation Time: 9:00 AM-6:30 PM


EARLE, Stephanie1, VASCIK, Bryce2, WALTON, Quentin2, LORD, Mark2 and KINNER, David2, (1)Department of Geosciences and Natural Resources, Western Carolina University, Cullowhee, NC 28723, (2)Geosciences and Natural Resources, Western Carolina University, Cullowhee, NC 28723,

Throughout the southern Appalachians, anthropogenic land disturbances in the late 1800s through much of the 1900s caused extensive soil erosion. Landscape and soil recovery rates from these past disturbances influence vegetation, water pathways, and water quality today. The purposes of this study were to determine the relation of soil physical and hydrologic properties to slope position, and to historic land covers and uses. A specific goal of the study was to determine the basic physical traits of soil profiles, including any evidence of soil truncation by erosion.

The study area, the Gribble Gap catchment (0.4 km2), is located in the headwaters of the Little Tennessee River watershed in the mountains of western North Carolina. Soil parent materials are saprolite developed from biotite-amphibole gneiss and colluvium. Logging and conversion of woodlands to pasture in the early 1900s led to extensive soil erosion through the mid-1900s; this land use history is common across the region.

Five soil profile sites were examined on a transect perpendicular to a slope from a ridgeline to the valley floor, and an additional site was downstream on a fan surface. Soil horizons were defined in the field, including depth to saprolite where present. Samples were analyzed for color, percent of clay-silt-sand-gravel, and organic carbon content. Soil moisture sensors were installed at each slope transect site at depths of 15, 35, and 75 cm.

At five sites, saprolite was found at depths of 75 to 185 cm. At the sixth site, on the valley floor abutting the slope and 1.6 m from a small creek, gleyed soils from 90 to 115 cm deep sit on coarse gravel, likely an old creek bottom. Soil profiles, especially on the upper slope, show evidence of truncation as indicated by a thin A horizon and a shallow, reddish, clay-rich B horizon. The valley-floor soil profile, however, is younger and appears to have a paleosol at 80 cm depth as indicated by a strong brown color (7.5YR 4/6) and high carbon content. We interpret most of the upper slope to be truncated by historic soil erosion and the valley floor profile to be a site of rapid deposition by products of soil erosion. Soil moisture data will be used to examine soil properties and make inferences about hydrologic pathways and groundwater recharge potential.